Efficient flow boiling in miniaturized systems is highly demanded due to its promise in developing high heat flux thermal management technologies for high power electronic and electric devices. In addition, micro- and nano-scale bio and chemical reactors can reach ultra-high efficiency by taking advantage of enhanced mass and heat transfer in miniaturized systems. Flow boiling in miniaturized channels has been extensively studied in the last decade.
The advances in nanofabrication and the demand of ultra-compact electronics and bio/chemical reactors have imposed extreme challenges in transporting ultrahigh heat fluxes. In theory, flow boiling in microchannels can achieve high heat and mass transport efficiency due to the high surface-area-to-volume ratio and the latent heat transport. However, in practice, the flow boiling in microchannels is limited by the viscous dominant flow and unpredicted flow pattern transitions, which result in pronounced instabilities and hence low heat and mass transfer efficiency.
Two-phase transport in microfluidic systems has attracted increasing attentions because of its wide range of application fields varying from biology to chemistry to energy and thermal management. The classic two-phase flow patterns in microchannels, which primarily include bubbly flow, slug flow, churn flow and annular flow, are diversified. However, classic two-phase flow patterns are diversified and show unpredictable transitions.
The nature of unpredictable two-phase flow pattern transitions in conventional microchannels could hinder the performance of two-phase transport and cause pronounced two-phase flow instabilities. In microfluidic systems, the formations of two-phase flow patterns are primarily governed by bubble confinements, liquid and vapor interactions, and internal governing forces.